The Place of Large Pore Membranes in the Treatment Portfolio of Patients on Hemodialysis

Abstract

Cardiovascular disease is a major concern in patients with end-stage kidney disease (ESKD). Inflammation induced by retention of uremic toxins, of which a substantial fraction has a molecular weight in the middle molecular range, has been associated with increased cardiovascular risk. In an attempt to reduce inflammation and thus cardiovascular toxicity in patients with ESKD, hemodiafiltration (HDF) has been promoted to enhance the clearance of middle molecular weight substances during dialysis. However, HDF increases the technical complexity and costs, and requires ultrapure dialysis fluid. Also, HDF becomes less beneficial when it is not possible to achieve sufficient convective volume in all patients. Over the last years, membranes with larger pore sizes, such as medium cut-off and high cut-off, have been introduced. These membranes, applied in hemodialysis mode, appear to have removal rates of middle molecular weight molecules that are comparable to those achieved with HDF, and could thus obviate the need for HDF. However, ultrapure dialysis fluid might still be required if there is a risk of transmigration of contaminants from the dialysate side into the blood because of the increased pore size. This transmigration of pyrogens might upregulate the expression of cytokines and other pro-inflammatory factors, and thus completely neutralize the beneficial effects of higher clearance of middle molecules. This chapter will explore the existing evidence on permeability of membranes with large pores for bacterial degradation products, and based on this information we will try to define the position of these novel membranes among the spectrum of existing membranes.

A randomized cross-over study with objective quantification of the performance of an asymmetric triacetate and a polysulfone dialysis membrane using different anticoagulation strategies

“…The removal of middle molecules, such as β2-microglobulin (β2M), and of protein-bound toxins, such as indoxylsulphate, is rather poor with conventional low-flux dialysis, whereas these contribute probably most to uraemic toxicity [ 1 , 2 ]. In an attempt to reduce inflammation and thus cardiovascular toxicity, the use of haemodiafiltration (HDF) or of more open membranes has been promoted to enhance clearance of middle molecular weight substances during dialysis [ 3 ].…”

Prescribing Hemodialysis or Hemodiafiltration: When One Size Does Not Fit All the Proposal of a Personalized Approach Based on Comorbidity and Nutritional Status

“…The advantages of high-efficiency HDF are less evident in older patients with shorter life expectancy, in which HD may be a reasonable choice, in particular when residual renal function is present; these patients may fail compensating for albumin loss, and shorter life expectancy makes it unlikely that they will develop dialysis-related amyloidosis, which generally takes at least ten years to become clinically evident [ 100 , 101 , 102 , 103 , 104 , 105 ].…”

Effect of air gap induction on the morphological microstructure of polyether sulfone hollow fiber membrane

“…10 Compared with ultrafiltration and nanofiltration membranes used in wastewater treatment, PES hollow fiber membranes used for hemodialysis require an outer surface with a large pore size to improve flux and an inner surface with a small pore size to achieve medium cut-off and high cut-off. 11,12 Hollow fiber membranes are often prepared through a dry-jet wet spinning process, in which the dope solution and bore solution are extruded from the spinneret to the coagulation bath through the air gap. The phase separation of the dope solution is driven by the nonsolvent action of the bore fluid and external coagulation bath.…”

“…Polyether sulfone (PES) hollow fiber membranes are widely used in hemodialysis applications owing to their excellent chemical and thermal stability and biocompatibility 10 . Compared with ultrafiltration and nanofiltration membranes used in wastewater treatment, PES hollow fiber membranes used for hemodialysis require an outer surface with a large pore size to improve flux and an inner surface with a small pore size to achieve medium cut‐off and high cut‐off 11,12 . Hollow fiber membranes are often prepared through a dry‐jet wet spinning process, in which the dope solution and bore solution are extruded from the spinneret to the coagulation bath through the air gap.…”